1. Field of the Invention
The invention relates to methods and devices for the transport of a liquid-gas mixture from an inlet to an outlet, and in particular to methods and devices utilizing a suction line that connects inlet and outlet chambers.
2. Description of Related Technology
Devices for the continuous transport of a liquid-gas mixture from an inlet chamber to a discharge chamber having a suction line connecting the inlet and discharge chambers are utilized in the paper making industry. For example, in steam-heated dryer cylinders of paper machines, condensate from an inner space of the cylinder can be removed therefrom with the aid of a syphon.
In such a paper machine cylinder, a certain amount of liquid must be transported from an inlet, which is at a first liquid level, to an outlet, which is at a second liquid level. At the same time, a certain amount of gas is transported together with the liquid. The gas transport may not be intended and may be undesirable.
When a syphon is utilized in a rotating dryer cylinder of a paper making machine, the syphon tube with its aspirating connection is immersed into condensate which forms on an inner wall of the dryer cylinder as an annular film. As long as the suction connection is below the condensate level, it is possible to remove condensate at a constant throughput (amount per unit time). However, since the thickness of the condensate film during the operation of the paper machine varies, the suction connection of the syphon might not always be fully immersed into the condensate. As a result, vapor (steam) as well as condensate is removed from the cylinder through the syphon. When gas flows through the syphon together with the liquid, the flow behavior becomes erratic. The larger the proportion of the gas, the larger the throughput of transported liquid because the gas entrains liquid with it as it flows through the syphon. However, since the amount of gas available in the inlet chamber is limited, the pressure in the inlet chamber drops very quickly, so that, due to a lack of pressure difference, liquid is no longer transported. At the same time, the thickness of the annular condensate film begins to grow again, so that the suction connection of the syphon is again immersed into the condensate and the cycle begins again. When two parallel syphons are used to remove condensate from a dryer cylinder, a situation readily occurs in which one syphon transports a large gas throughput while condensate flows through the second syphon.
Thus, in order to remove condensate from steam-heated rotating dryer cylinders of paper making machines, and to achieve stable, uninterrupted condensate flow, large amounts of steam have been allowed to flow through the syphon, together with condensate. The volumetric ratio of the steam throughput to condensate throughput must typically exceed the value of 50 in order to ensure a stable condensate flow.
It is known that bores disposed above the syphon suction connection can be provided through which additional steam can be introduced in order to avoid complete breakdown of the condensate stream. However, the bores for additional steam must be of a relatively large cross-section in order to provide the desired effect. When using such additional steam bores, a low ratio of steam throughput to condensate throughput cannot be achieved.